So there was this little village that was run over by barbarians every year. The barbarians stole the cattle and burned down the harvest, bringing the village to the brink of destruction. And because resources were scarce, even when the barbarians skipped a year, the villagers were still fighting among themselves. Poorer inhabitants stole from the richer ones. People viewed each other with suspicion. Life was harsh and not much happiness was found.
At some point the elders of all the village’s families came together, and decided that they needed to cooperate to keep the barbarians out. They decided to all pitch in and raise a fence. All the families contributed to a common resource pool, from which they supported armed soldiers that from then on guarded the surroundings of the village.
The barbarians tried to attack several more years, but the village was now well defended and managed to keep them at bay. The barbarians, no longer having the village as an easy source of sustenance, went to seek their luck elsewhere.
The village prospered. Now the problems with the barbarians were solved, the villagers were able to make life a lot better for themselves. They started trading, and created a welfare system that helped everybody to have better and more secure lives. The elders decided that each family should contribute to the good of everybody, the stronger and richer ones contributing a bit more than the weaker and poorer ones. Maybe the contributions were a bit unbalanced in that sense, but in the end everybody was better off by this organized cooperation.
The years went by and many villagers forgot why they had come together in the first place. Few remembered how things were before they banded up. Some of the richer families started to grumble: why were they supposed to contribute so much for those lazy, poor, third-rate families? And what about that council of elders? Were they really needed? Sitting on their lazy behinds, making rules that were obstructing freedoms, and getting fed for doing that and not much else. Who needs them?
One day, one of the richer families decided to drop out. They had taken a vote amongst their family members, and the majority had decided that they no longer were going to contribute to the village. They did not need the others. They had plenty of stuff for themselves, and they could collaborate with whomever wanted. And why not drop out? The village was safe, the fence was up, the guards were parading, and it was not as if that all would end if they decided no longer to be involved with the rest of the village.
“Basically,” they reasoned: “cooperation is a good thing, so it is great that the others are cooperating, but we gain much more if we do not contribute to the cooperation, as we will still reap almost all the benefits of the cooperation of the others, while bearing none of the costs!”
Of course, you can guess what happened. After the first family withdrew from contributing to the village, and evidently did not seem to suffer much from it, the next family which considered itself a net contributor dropped out as well. Quickly followed by the next, and the next, and the next. Trade became a hassle, the poorer families started to steal from the richer ones, nobody paid for the guards anymore, and the fence fell into disrepair. The barbarians, who were still in the neighborhood, took up their old habits, and plundering started all over again.
And sitting in the ruins of their village, which only recently had been prospering, the remaining villagers wondered why they had not bothered to ask themselves whether they had been better or worse off before they started cooperating.